Chlorophyll a fluorescence analysis reveals divergent photosystem II responses to saline, alkaline and saline-alkaline stresses in the two Lotus japonicus model ecotypes MG20 and Gifu-129

CESAR DANIEL BORDENAVE; RUBEN ROCCO; SANTIAGO MAIALE; MARÍA PAULA CAMPESTRE; OSCAR RUIZ; ANDRES ALBERTO RODRIGUEZ; ANA BERNARDINA MENENDEZ

ACTA PHYSIOLOGIAE PLANTARUM

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2019

0137-5881

Saline and alkaline stresses affect more than 10% of the World?s arable land, limitingagricultural production. Salt-induced stress may affect the Photosystem II (PSII)function, altering fluorescence emission. Therefore, changes in fluorescence are usedto quantify and analyze abiotic stress responses in plants. So far, no study has beenfocused on the response of PSII to saline, alkaline and saline-alkaline stresses in themodel legume Lotus japonicus. For the saline, alkaline and saline-alkaline treatments,plants of the L. japonicus ecotypes MG20 and Gifu-129 were cultivated in sand withnutrient solution added with NaCl and NaHCO3 in different proportions. Growth, gasexchange, and chlorophyll a fluorescence transient kinetic and OJIP parameters weremeasured, and chlorophyll a and b determined. The analysis of the kinetic ofchlorophyll a fluorescence showed that NaCl-derived stress sources affect thephotochemical events in PSII in both ecotypes, being this effect more evident underhigher pH condition, whereas alkalinity per se has a mild or no effect on these events.The saline-alkaline stress induced a more severe effect on Gifu B-129, compared withMiyakojima MG20, whereas NaCl improved primary photochemistry in MG20. Ourresults allow us to accept the hypothesis that both ecotypes deploy differentialresponses under the three stressful treatments and that the saline-alkaline stress causes higher damage levels than saline and alkaline stresses alone in relation withstructures and sub-processes of the PSII.